Improvement in the manufacture op photographic pictures



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.IOll'N ROBERT JOHNSON, OF LONDON, ENG-LAND.

- Letters Patent N 92,836, ZatelJuly 20, 1869.

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IMPROVEMENT 1N THE' MANUPACTURE or*1PH'oro eflmpnncl PICTURES.

The Schedule referred to in these Letters Patent and making part of thesame.

To all whom it moy'co'ncern:

Be it known that I, thenndersigned, JOHN ROBERT JoiFXsoN, of No. 5Haymarket, Londoma director of' the Autotype Printing and PublishingCompany, limited, have invented Improvements in the llianu'tacture orProduction of Photographic Pictures; and I do hereby declare that thefollowing,l is a description of my i11- vention, suflicient to enablethose skilled in the art to practise it.

My invention relates exclusively to that class of photographic pictgrein which the images are produced by a pigment mixed with gelatine, andits analogues, and a bichroinate. The gelatine, becomingr insolubleunder the joint action of light and the chromic salt, imprisons thepigment forming the images, which are revealed when the compound isplaced in warm The pigment compound unacted upon, washes away, and thepicture formed of the compound renderedinsoluble remains. This operationis calledl the development of the picture.

Poitevin was the first to attempt to form such pictures. He spread thesensitive pigment compound upon paper, and printed through a negativethereon, washing away, subsequently, the compound unacted u'pon; but asinuch of' this was below thc images formed on the surface,the latterwere removed with the soluble substratum.

Pouncy succeeded better by brushing the same sensitive compound into thesubstance of a porous paper, which held the images, notwithstanding thesoluble matter below them.

, 'Burnet and Blair printed the. sensitive compound from behind, washingaway the soluble matter in front of or above the insoluble picture.

Fargier spread the sensitive compound upon glass or other plane,impermeable surface printed thereon, and then covered the picture with alayer ofcollodion. When the whole was plunged into water, the collodionfloated with the` insoluble picture attached thereto. Nlien this. wassufficiently developed, the film was' caught upon a piece of'gelatiniacdpaper, which formed its permanent support.

Swan formed a tissue of' collodion and gelatine, printed upon thecollodiou side, and then attached that side to a permanent support ofpapen. glass, earthenwarc,85o., by ineans of albumen, rendered insolubleby alcohol or heat, or by means of starch-paste. 'lhe pictures` soproduced were, however, reversed. To

produce them 'non-reversed, he mounted the tissue,

printed side'downward,,upon paper coated with India rubber, by means of.a powerful 'press developed the picture upon this temporary support, andwhen dry attached th'e picture to a piece of paper ,by means of'`gelatine, &c. He then applied benzole to the India- !ubber paper, whichenabled the operz'ttor to strip ol'll picture.

that paper, leaving the picture attached permanently to the gelatinepaper, the images being then in their correct position. Swan also use/das a tissue the pie'- ment spread upon'paper like Poitevin. Edwardssubstituted gelatine, rendered partly insoluble by alum, 85e., foralbunicn, rendered insoluble for the purpose of receiving the pictureduring development and forniing; the peimanent support.

My invention consists in the use of shellac or other resinous bdy,dissolved in very weak ammonia, i11- stead of the albumen, starch, orgelatine rendered insoluble, employed as above-for permanentlyreceiving` and mounting the picture on its permanent support. -The resinis unaffected by moisture, and does not turn yellow by age, and istherefore very superior to the substances heretofore used for thispurpose.

` I operate in the following manner:

I coat paper or any other plane surface, permeable "or impermeable, withthe sensitive pigment compound.

When dry, I print upon this, and I immerse the printed sheet in waterfor a few seconds, until the gelatine has absorbed a portion only of thewater which it will take up. I apply the wet sheet, face downward, uponthe permanent support, (under water, if p0ssible,) and with a flat brushor smooth straight edge, I scrape off the surplus water, 'and with itthe air-bubbles. I then place the whole in ahorizontal position for tenminutes on. more, until the gelatine has absorbed the whole of the waterremaining. The two surfaces will now be found to adhere, and I thenplunge them into warm water, say at 10,0O Fahrenheit, until the picturelbe developed.- I finally wash in cold water, and dry.

' Any impermeable hat suif'ace may be used, as

- lass metal 'a an-ware varnished ianel aintcd v a J 1 1 cloth, waxed oroiled paper, prepared canvas-paper, coated with India rubber, or othersubstance impermeable to air and water, Sac. i

If glass or other transparent medium has beenl used, as the support, thepicture is non-reversed, when viewed through the glass, but in all othercases it is reversed. l

\If' the support be impermeable to air and water, no preparation isnecessary to enable `it to receive the It it be' opaque, like paper, Icoat it, pre.- viously to the application of the picture, with solutionshellac in ammonia. Vhen the Volatile ammoniahas evaporated, the vresinis left in an insoluble state, but still moist and adhesive, and highlyfavorable to the reception of the gelatine film.

\Vl1en the picture contains large white spaces and much delicate halftone, I give, as au extra precaution,- a thinflayerof the resin to thepermanent supports position, I use an impermeable surface, such as glassor metal plates, as a temporary support, having previously given them athin smear or coating of some.

solid, fatty body. I prefer for this purpose a compound of beeswax andyellow resin, in the proportion ol' three of the former to one of thelatter.

lA find, also, that a film of India ru'bber or oi gutte-v pereha, ii'ot' a moderate thickness,obtained by pouring on the glass or other platea solution of these substances in a volatile solvent, will eiect thelike result, inasmuch as these substances have less adhesion to apolishedsuriacc than the iihn to the paper to which itis cemented. TheIndia rubber, &e., therefore comes away from the plate attached tothepieture, from which it is easily removed by friction,

It will be observed that the India rubber, Sac., is used, not as acementing Substance, to eii'ect adhesion,

but as a means of separation, and such use diti'ers greatly from that ofSwan.

The surface, thus prepared, is then 'treated as already described. \Vhenthe pictureis dry, it is mounted upon paper, to whieh it is cemented bythe solution of shcllae, and when again dry it peels readily from thewaxed plate, particularly if the latter be heated or has been dried in awarm stove.

Having now described the naturel'of my invmxtion,A

and the mode of carrying it out, I would state that l 1. The use ofshellae and its analogues, used in the way described, for the purpose ofreceiving and mounting the pigmentpioture-tihn upon its permanentsupport.

2. The mode of' mounting and developing the pigment picture-film upon ateniporary support, by means ofthe intervening surface of a solid,fatty, or resiuous body, infusible at the temperature of development,

Aand retaining the picture during that process, but which allows ot' theremoval ofthe picture when ee` mented to its permanent support.

London, 20th March, 1869.

JOHN ROBT. JOHNSON..

XVitnesses:

G. F. WARREN, luos. BROWN,

Both ofNo. 17 G'racchureh Straat, London.

